Ondetti et al. in U.S. Pat. No. 4,105,776 disclose various mercaptoacyl, acylmercaptoacyl, substituted mercaptoacyl, and disulfideacyl N-substituted prolines. The proline ring can be substituted, for example, in the 4-position by a hydroxy or lower alkyl group. Ondetti et al. disclose that these compounds are useful as hypotensive agents due to their angiotensin converting enzyme inhibitory activity. Among the compounds disclosed by Ondetti et al. is captopril, 1-(D-3-mercapto-2-methylpropanoyl)-L-proline.
Wong et al., "The In Vitro Metabolism of .sup.14 C-Captopril In The Blood of Rats, Dogs and Humans", Pharmacologist, Vol. 21, p. 173 (August, 1979) identifies captopril-glutathione and captoprilcysteine mixed disulfides as metabolites of captopril.
Ondetti et al. in U.S. Pat. No. 4,154,935 disclose that various mercaptoacyl 4-halo or 4,4-halo substituted prolines and the corresponding disulfides are useful hypotensive agents.
Ondetti in U.S. Pat. No. 4,192,878 disclose that various mercaptoacyl thiazolidinecarboxylic acids are useful hypotensive agents.
Ondetti et al. in U.S. Pat. No. 4,154,942 discloses that various mercaptoacyl 3,4-dehydroprolines and the corresponding disulfides are useful hypotensive agents.